A waveguide orthomode transducer (OMT) is a three-port radio frequency device that can be used as a polarization diplexer for combining or separating two, respectively orthogonal, linearly polarized signals. Two of the three ports are coupled with two respective waveguides carrying single linearly polarized electromagnetic signals, whereas, the third of the three ports is coupled with a waveguide carrying two orthogonal linear polarized signals.
An OMT can provide for a concurrent transmission of signals of differing frequencies and differing linear polarizations through a common antenna and are therefore useful for many communication satellite applications. There are various types of OMTs. Some are based on turnstile waveguide junctions such as described in the present inventor's U.S. Pat. No. 7,397,323. In other types of OMTs, the two waveguides carrying single polarized electromagnetic signals are perpendicular to each other and/or to the waveguide carrying the two orthogonal linear polarized signals.
Modern satellites can include antennas having a reflector with a feed array located in its focal plane while using orthogonal linearly polarized signals. Satellite payload requirements are driving a need for feed arrays with numerous feed array elements. The size of each feed array element is, desirably, as small as possible. In the absence of the presently disclosed techniques, the size of such feed arrays may be driven by the OMT size.
Accordingly, there is a need for a more compact, high performance, OMT design.